1. Field of the Invention
The present invention relates to release layer paste used for production of a multilayer ceramic-capacitor or other multilayer type electronic device and a method of production of a multilayer type electronic device using the release layer paste.
2. Description of the Related Art
In recent years, due to the increasingly smaller sizes of electronic apparatuses, multilayer ceramic capacitors and other multilayer type electronic devices have become increasingly compact in size and sophisticated in performance. The thicknesses of the interlayer dielectric layers of multilayer type electronic devices (dielectric layers sandwiched between pairs of internal electrodes) have become 1 μm or less—enabling over 800 stacked layers. In the process of production of such electronic devices, the thicknesses of the green sheets able to form-the dielectric layers after firing have become extremely thin (usually 1.5 μm or less), so at the time of formation of the electrode layers by the printing method, the solvent of the electrode layer paste causes the green sheets to dissolve, that is, the so-called “sheet attack” phenomenon becomes a problem. This sheet attack phenomenon leads directly to defects of the green sheets and short-circuit defects, so is a problem which absolutely must be solved for making the layers thinner.
To eliminate this sheet attack, Japanese Patent Publication (A) No. 63-51616, Japanese Patent Publication (A) No. 3-250612, and Japanese Patent Publication (A) No. 7-312326 propose forming an electrode layer paste on a supporting film in a predetermined pattern, then drying it so as to separately prepare a dry electrode layer, then transferring this dry electrode layer to the surface of a green sheet or the surface of a laminate of green sheets so as to transfer the predetermined pattern of the electrode.
However, Japanese Patent Publication (A) No. 63-51616, Japanese Patent Publication (A) No. 3-250612, and Japanese Patent Publication (A) No. 7-312326 had the problem of a difficulty of peeling off the predetermined pattern of the electrode layer from the supporting film.
Therefore, the inventors proposed technology for forming a release layer between a supporting film and a predetermined pattern of an electrode layer so as to improve the peelability of the electrode layer (see Japanese Patent Publication (A) No. 2003-197457).
In Japanese Patent Publication (A) No. 2003-197457, as the release layer paste used for forming the release layer, use was made of one comprised of a binder dissolved in a solvent to form an organic vehicle into which at least a ceramic powder and plasticizer were dissolved. As the binder in the organic vehicle, one the same as the binder contained in the green sheet, that is, polyvinyl butyral (acetal group R═C3H7), which is a type of polyvinyl acetal-based resin, was used. Further, as the solvent in the organic vehicle contained in the electrode layer paste used for forming the predetermined patterns of electrode layers, terpineol, dehydroterpineol, etc. was used.
However, if using an electrode layer paste using terpineol or dehydroterpineol as a solvent together with a release layer using a butyral resin as a binder, the solvent of the electrode layer paste causes sheet attack at the release layer. Further, at the time of printing the electrode layer paste, the release layer is ablated and residue sometimes generated.
Sheet attack of the release layer becomes a cause of bleedout, shedding, and pinholes at the electrode layer or blank pattern layer formed on the surface of the release layer. Further, the ablation of the release layer causes defects (structural defects) at the time of stacking and in turn can increase the short-circuit defects of the final multilayer type electronic device.
Therefore, prevention of sheet attack and ablation of the release layer has been strongly demanded.